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I wanted to give Firefox for Android a try (I'm a long-time Chrome user), but after installing it from the Play Store, I discovered it refuses to load any website, always showing this security warning that cannot be ignored:

This website requires a secure connection

This happens on all sites and only on Firefox for Android, the same sites load correctly in Chrome and also load correctly in Firefox running on a Windows computer that is on the same network as my Android device.

Any clues as to why this is happening? I'm running Firefox 105.1.0 on Android 12.

Andrew T.
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Master_T
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1 Answers1

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After doing more digging, it seems the problem was my adblocker (AdGuard). It uses a locally installed CA certificate in order to filter HTTPS traffic. By default Firefox ignores local CA certificates, it has its own list of trusted CAs. Quite dumb in my opinion, but luckily local CA certificates can be enabled by following this guide:

https://kb.adguard.com/en/android/solving-problems/firefox-certificates

Master_T
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